In hydrocarbon exploration and/or production, control of a well may be accidentally lost resulting in a blowout. During the blowout, well fluids flowing to the surface may cause environmental damage and often catch fire. Because economic and environmental loss occur at an increasing rate during the duration of a blowout, great effort is expended in trying to control the well. This usually involves drilling one or more relief wells. A relief well is a well that is drilled at a distance away from the target well (e.g., the blowout well), and is intended to intersect or come within an effective distance of the target well so that mud can be pumped into the target well to prevent formation fluid from reaching the surface.
A relief well must be drilled with great directional accuracy in order for the relief well to intersect the target well. For example, drilling of the relief may begin at location distant (e.g., 1000 feet or more) from the surface location of the target well, and the bore diameter of the target well may be relatively small (e.g., one foot). Consequently, improved techniques for steering a relief well to intersect a target well are desirable.